As far as the real presence and transubstantiation goes it is pronounced by Jesus in the gospel of John.
John 6:41-69
**41At this the Jews began to grumble about him because he said, “I am the bread that came down from heaven.” 42They said, “Is this not Jesus, the son of Joseph, whose father and mother we know? How can he now say, ‘I came down from heaven’?” **
43"Stop grumbling among yourselves," Jesus answered. 44"No one can come to me unless the Father who sent me draws him, and I will raise him up at the last day. 45It is written in the Prophets: 'They will all be taught by God.'a] Everyone who listens to the Father and learns from him comes to me. 46No one has seen the Father except the one who is from God; only he has seen the Father. 47I tell you the truth, he who believes has everlasting life. 48I am the bread of life. 49Your forefathers ate the manna in the desert, yet they died. 50But here is the bread that comes down from heaven, which a man may eat and not die. 51I am the living bread that came down from heaven. If anyone eats of this bread, he will live forever. This bread is my flesh, which I will give for the life of the world."
**52Then the Jews began to argue sharply among themselves, “How can this man give us his flesh to eat?” **
**53Jesus said to them, “I tell you the truth, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. 54Whoever eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day. 55For my flesh is real food and my blood is real drink. 56Whoever eats my flesh and drinks my blood remains in me, and I in him. 57Just as the living Father sent me and I live because of the Father, so the one who feeds on me will live because of me. 58This is the bread that came down from heaven. Your forefathers ate manna and died, but he who feeds on this bread will live forever.” 59He said this while teaching in the synagogue in Capernaum. **Many Disciples Desert Jesus ****
60On hearing it, many of his disciples said, “This is a hard teaching. Who can accept it?”
61Aware that his disciples were grumbling about this, Jesus said to them, “Does this offend you? 62What if you see the Son of Man ascend to where he was before! 63The Spirit gives life; the flesh counts for nothing. The words I have spoken to you are spirit**(“
John 6: 41-71; NIV - At this the Jews there began to grumble - Bible Gateway”)] and they are life. 64Yet there are some of you who do not believe.” For Jesus had known from the beginning which of them did not believe and who would betray him. 65He went on to say, “This is why I told you that no one can come to me unless the Father has enabled him.”
66From this time many of his disciples turned back and no longer followed him.
67"You do not want to leave too, do you?" Jesus asked the Twelve. 68Simon Peter answered him, “Lord, to whom shall we go? You have the words of eternal life. 69We believe and know that you are the Holy One of God.”
**So, like modern day protestants, those listening to Jesus at the time did not understand what he meant by saying he would be present in the Eucharist. He repeated himself and tried to get the message through. If he wanted the Eucharist to be just a symbol don’t you think he would have made it clearer to the people, and his disciples when he re-explained what he was saying. Also why would the disciples leave him saying the teaching was too hard if it was just to be meant as symbolism. The belief in the Real Presence requires strong faith and it is, as taught by the Church and by Scripture, the greatest of all the miracles performed by Jesus Christ. **